Does data get flushed to the DB on commit when in Commit Opt

[paulsmith001]

When using commit option A, I guess there is no need for a container to flush data to the DB after a commit - after all, in commit option A the container has sole access to the DB.
In my tests however (using JBoss), I notice that the data does appear to be flushed to the DB. Can I rely on this behaviour? Is it in the spec or is it up to the implementation to decide what to do?

Thanks,
Paul

[luc.texier]

The container must commit to guarantee ACID transactions.

http://www.nusphere.com/products/library/acid_transactions.htm

Durability
Once a transaction is committed, its effects are guaranteed to persist even in the event of subsequent system failures. Until the transaction commits, not only are any changes made by that transaction not durable, but are guaranteed not to persist in the face of a system failure, as crash recovery will rollback their effects.